Unit Testing - Core Data - page 179

override func tearDown() {
super . tearDown ()
camperService = nil
coreDataStack = nil
}
tearDown is the opposite of setUp , and is called after each test executes. Here, the
method will simply make all the properties nil , resetting the CoreDataStack after
every test.
There's only a single method on CamperService at this point, and that is
addCamper(_:phonenumber:) . Still in CamperServiceTests.swift , create a new
method to test addCamper :
func testAddCamper() {
let camper = camperService . addCamper ( "Bacon Lover" ,
phoneNumber: "910-543-9000" )
XCTAssertNotNil (camper, "Camper should not be nil" )
XCTAssertTrue (camper?. fullName == "Bacon Lover" )
XCTAssertTrue (camper?. phoneNumber == "910-543-9000" )
}
You create a camper with certain properties, then check to confirm that a camper
exists with the properties you expect.
Remove the testExample and testPerformanceExample methods from the class.
It's a simple test, but it ensures that if any logic inside of addCamper is modified, the
basic operation doesn't change. For example, if you add some new data validation
logic to prevent bacon-loving people from reserving campgrounds, addCamper might
return nil. This test would then fail, alerting you that either you made a mistake in
the validation or that the test needs to be updated.